DESCRIPTION: The purpose of this study is to design, implement, and evaluate a recreation site-based obesity preventio and control intervention for 7-9 year old children and their families by targeting physical activity and dietar behaviors. The intervention will target the home as well as community environment (specifically urba recreation centers;but also, other aspects of the neighborhood). This study will produce innovations i obesity interventions and the understanding of mediators of change. Recreationcenters are an importan public resource whose contribution to physical activity promotion is unknown but has the potential to b significant The primary aim is to evaluate the effectiveness of a multi-level intervention to prevent the onset o overweight and obesity in 7-9 year old children. The recreation center site intervention emphasizes change in quantity and quality of physical activity and nutrition-related offerings within the centers. The home sit intervention will target the home and household rule setting delivered via recreation center-based communit health advisors and tailored to the needs of the family. Community health advisors will work in home an neighborhood environments to advocate environmental change Secondary research aims include 1. To modify the setting and enforcement of rules and to establish home environmental controls o childhood nutrition and physical activity behaviors;and to assess the extent to which changes in thes mediators lead to changes in proximal outcomes (physical activity, sedentary behavior, and nutrition) 2. To determine and attempt to modify patterns of setting and enforcement of rules and hom environmental control of childhood nutrition and physical activity, and to assess the extent to which change in these mediators lead to changes in proximal outcomes (physical activity, sedentary behavior, an nutrition) 3. To determine mediators (barriers and facilitators) of healthy and unhealthy eating and physica activity/sedentary behavior in recreation centers, and to assess the extent to which changes in thes mediators lead to changes in proximal outcomes (physical activity, sedentary behavior, and nutrition) 4. To develop and apply observational measures of physical activity and dietary behaviors (adapted fro SOPLAY) appropriate for recreation centers and parks 5. To assess the impact of hypothesized intervention moderator variables (e.g., race/ethnicity demographics, acculturation, immutable environmental factors) on behavioral and weight outcomes.